This invention relates to an apparatus and method for cooling hot areas of infrared conduits in a gas fired infrared radiant heater.
Gas fired infrared heaters typically are used in large industrial settings. A gas heater burns natural gas, propane, or similar combustible gases and the combustion by-products or exhaust gasses pass through a heat exchanger conduit to heat a building. The gas heater creates a hot exhaust gas stream flowing through heat exchanger conduits, causing the conduits to become hot and radiate energy waves therefrom. Reflector plates are often used to reflect the energy waves toward the desired location, usually toward the floor, where the infrared energy waves are converted into heat.
In some environments it is desirable that no surface temperature exceed predefined limits. Often in certain environments, federal or state restrictions limit the maximum surface temperature on any surface within an enclosed area.
Prior art infrared heaters cannot be used in these of environments because the temperatures on their surfaces exceed these limits. Therefore, often no heat is provided in these environments for this reason.
The present invention limits the peak temperature on the external surface of a conduit associated with infrared gas burners by cooling the conduit and/or shutting off the burner if necessary. At least one thermocouple, or other temperature measuring device, is installed at a predetermined point on the conduit corresponding to the peak temperature location for signaling a control valve to shut off the burner when the peak temperature on the external surface of the conduit approaches a predefined limit.
An improvement to the infrared heater system provides for a forced air convective cooling system, such as a fan or blower, with proper velocity vectoring via a deflector or other flow directing device to cool a conduit hot spot. The cooling system can be designed as a part of a control system to operate the blower. The convective cooling allows the burner to run continuously for a longer period of time and, therefore, more efficiently with a more uniform temperature gradient throughout the tubing system. This mode of operation produces more usable heat for a given amount of fuel consumed.
Other applications of the present invention will become apparent to those skilled in the art when the following description of the best mode contemplated for practicing the invention is read in conjunction with the accompanying drawings.